Combined doctor means



April 2, 1968 o. BEALL ETAL 3,375,305

COMBINED DOCTOR MEANS Filed Sept. 2, 1965 3 Sheets-Sheet 1 P1I3-. 1A.'

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INVEN TORS. RICHARD 0. BEALL and HARRY M. 7mm, JR.

Attorney p -2,1968 R. (iBEALL TA; 3,375,805

COMBINED DOCTOR MEANS.

Filed Sept. 2, 1965 r s Sheets-Sheet z Attorney April 2, 1968 o. BEALL ETAL COMBINED DOCTOR MEANS 5 Sheets-Sheet 5 Filed Sept. 2, 1965 PIE}. 4.

Oil Bath Level M \a n 4 v E Te me Me ml Leva/ RICHARD 0 1 HARRY M. BERNARD, JR.

INVENTORS. BEALL and At rorney United States Patent 6 3,375,805 COMBINED DOCTOR MEANS Richard 0. Beall, Pittsburgh, and Harry M. Bernard, In,

West Mifiin, Pa., assignors to United States Steel Corporation, a corporation of Delaware Filed Sept. 2, 1965, Ser. No. 484,670 1 Claim. (Cl. 118-63) ABSTRACT OF THE DISCLOSURE Combined doctor means wherein a single hanger disposed above a pool of coating material supports, in vertical arrangement and in series, a pair of opposed doctor blades and a pair of opposed air knife means.

This invention relates to the hot metal coating of strip product and more particularly to the terne coating of steel strip.

Terne metal is an alloy of lead and tin frequently applied to steel sheet or strip by passing it through a molten bath of such metal whereby the terne metal partially alloys with the steel base to form a tight bond therewith. The terne metal is applied to the steel base primarily to obtain the corrosion resistance of the lead but since lead does not alloy with iron, the tin is added which readily alloys with the steel base and at the same time forms a solid solution with the lead. Since the terne coating is cathodic to iron under most environments and will thereby increase the corrosive action if a portion of the steel is exposed to such environment because of pinholes or other discontinuities on the coating, it is essential that a continuous coating free of defects be obtained. A factor that militates against more widespread use of terne coatings is the dull appearance thereof.

It is accordingly an object of this invention to produce terne coated product in a more eflicient manner.

It is a further object of the present invention to produce terne coated product of high quality and pleasing appearance.

The foregoing and further objects will become apparent from the following specification when read in conjunction with the attached drawings wherein:

FIGURES 1A, B and C are simplified diagrams of a continuous terne coating line embodying our invention;

FIGURE 2 is an enlarged view of the coating tank partially broken away to show the rigging disposed therein;

FIGURE 3 is an enlarged view of the strip wiper of our invention; and

FIGURE 4 is an isometric view of the rigging showing the coating rolls, strip wiper and air jet arrangement.

Referring more particularly to the drawings the numeral 2 designates a suitable uncoiler in which the strip 8 is fed to the coating line preferably through a suitable leveller 4 and welder 6 for joining successive coils together. Thereafter the strip passes through drag bridles 8 and 10 disposed at the entry and exit end of a looper 12 to provide continuous movement of the strip through the cleaning and coating stages of the line while the incoming strip is stopped to weld the coil ends. Thus after passing through drive bridle 10 and the looper 12, the strip passes successively through an alkaline cleaner 14, brushes 16, acid pickle tank 18, a water tank 20, brushes 22 and acid clip 24 before entering the coiling pct 26 containing molten terne metal. The terne metal is maintained molten by conventional heating means. A flux holder 28- is dis- 3,375,805 Patented Apr. 2, 1968 posed around the strip pass line on the entry side of the pot 26. After passing partially around a sink roll 29 in the pot carried by the rigging 46, the strip travels vertically upwardly through an oil bath 30 which floats on the molten terne metal at the exit side of the pot. The oil may be palm oil, fish oil, mineral oil or combinations thereof. Two pairs of conventional coating rolls 32 are also disposed in the oil bath. Pursuant to the invention, adjustable wipers 34 such as asbestos or the like, are disposed in the oil :bath and engage the strip after it has been through the coating rolls. As shown in FIGURES 3 and 4, the asbestos wipers are mounted in slots 36 in transverse members 38 carried by arms 40a and 40b attached to rotatable bars 42 journaled in angles 44 which are fixed to rigging 46. Since the coating rolls and sink roll form part of the rigging, these members can be readily removed from the coating bath as a unit. Bolts 48 adjustably connect the arms 40b to a bar 50 to control the position of the left-hand wiper with respect to the pass line by adjusting nuts 54 and lock nuts 56. Bolts 52 adjustably connect arms 40a to the bar 50 so the pressure exerted by the wipers 34 can be adjusted to suitably control the thickness of the terne coating.

High pressure air blasts from jets 60 in pipes 62 are directed downwardly onto both sides of the strip across the full width thereof shortly after the coated strip emerges from the oil bath through slots 64 of frame members 66 of the rigging 46. The pipes 62 are connected to a suitable source (not shown) of air under pressure. While the asbestos wipers operating in the oil bath smooth the terne coating and producing an even coat across the width of the strip, the coated strip as it leaves the oil bath carries a very heavy oil strip on its surface. This does not drain back evenly and thus may leave some oil marks or streaks. These however are obviated by the downwardly directed air blasts. The air blasts have an additional smoothing effect on the coating and at the same time efficiently remove the oil so that the remaining oil is readily removed by alkaline cleaning. The conventional branner whereby the strip is contacted by bran, sawdust or the like and then scrubbed to remove the oil, is eliminated by the use of the asbestos wipers and air blasts.

Following passage of the strip between the headers 66, the strip continues its vertical travel until the terne coating has solidified. It then passes over a guide roll 68 and downwardly under roll 70. -It then passes over tanks 72, 74 and 76 where it is successively treated with a mineral spirit, hot water with an alkaline cleaner additive and finally a hot water rinse. Thereafter it passes through a dryer 78 and may then be cut into sheets or recoiled. The strip so treated has a smooth even bright coating of terne metal.

While we have shown and described one specific embodiment of our invention, it will be understood that this embodiment is merely for the purpose of illustration and description and that various other forms may be devised within the scope of our invention, as defined in the appended claim.

We claim:

1. In apparatus for wiping continuous metal strip as it emerges coated with molten terne metal and oil from a molten bath of terne meta-l through a bath of oil including at least a pair of coating rolls in the oil bath between which said strip passes and is engaged by before it emerges from said oil bath the improvement therewith of a frame support disposed above said oil bath, a pair of arms each pivotally mounted by one end on said frame 4 support and depending therefrom toward said oil bath, References Cited the lower ends of said arms being submerged in said oil UNITED STATES PATENTS bath above said coatmg rolls one on each s1de of the path 7 of said strip, wiper means carried by the submerged ends 12/1907 Porter et 118403 of said arms wiping said strip only after its passage be- 5 1,365,414 1/1921 KPchendorfer 118103 tween all of said pairs of coating rolls and prior to its 1,810,699 6/1931 Dleschel' 118403 emergence from said oil bath, means for moving said 1,876,278 9/1932 Dlescher arms together to adjust the pressure exerted by the wipers FOREIGN PATENTS on said strip, and means carried by said frame support dis- 27,425 1903 Great Britain.

posed above said wiper means and above said oil bath m for directing jets of air downwardly on said strip across M 1 KA LA E the full Width thereof as it emerges from said oil bath. v O S P Hmary xamme 

